The chloroplast membrane system can be used as a model membrane for the study of the control of membrane biogenesis. In plants showing light-dependent membrane synthesis, the chloroplast can provide a source of synchronously developed membranes for analysis. Such a membrane system, which is highly integrated, can be used to delineate the levels and nature of the control mechanisms functioning in its synthesis and assembly into a functional cellular component. The aim of the proposed research is to define the control of chloroplast membrane biogenesis by studying the control of chlorophyll-protein synthesis in mutants, and environmentally and metabolically modulated developing systems from Hordeum vulgare. This study will examine these developmental processes in isolated protoplasts as well as in isolated etio-chloroplasts and developing chloroplasts. In particular, two chlorophyll-proteins will be studied. The P700-chlorophyll a-protein which is the reaction center complex of photosystem I and the light-harvesting chlorophyll a/b-protein which is the major antennae component of the photosynthetic apparatus. These two chlorophyll-protein complexes account for at least 65% of the total membrane protein and an equal amount of the total membrane chlorophyll. Methods of analysis will involve following the time course of synthesis of these components or their polypeptides during light-initiated chloroplast development. The presence of these membrane constituents in etiolated tissue will be examined. The complexes and their apo-proteins will be detected and analyzed by various protein chemistry techniques. A major consideration of the proposal is to define whether chlorophyll or chlorophyll-binding protein synthesis is the major rate limiting step controlling membrane biogenesis.